By A.J. Hostetler 

More adults – 42% – in the United States have fatty liver disease than previously estimated, and the disease hits Hispanics harder than other groups, according to research led by a Virginia Commonwealth University hepatologist.

The new study, published Oct. 29, in the journal Nature Communications Medicine, sheds light on how different forms of liver disease, including those linked to metabolic issues and alcohol, affect various groups.

“This study highlights a significant health issue that affects a large portion of the U.S. population, and it shows that certain groups are at a higher risk,” said the study’s corresponding author, Juan Pablo Arab, M.D., a hepatologist with VCU’s Stravitz-Sanyal Institute for Liver Disease and Metabolic Health and its director of alcohol sciences. “We hope these findings will guide more targeted health interventions to reduce the burden of liver disease, especially in high-risk communities.”

Steatotic liver disease, or fatty liver disease, is a broad term for conditions where fat builds up in the liver and damages the liver tissue. In 2023, the hepatology community refined that definition to include metabolic dysfunction-associated steatotic liver disease, alcohol-associated liver disease and a combination of both called MetALD. This updated classification has helped doctors and researchers better understand how MASLD, ALD and MetALD develop and who is affected the most.

In the new study, the researchers wanted to know more about how the new classification might affect prevalence rates among different groups. Using data from NHANES – the National Health and Nutrition Examination Survey – from 2017-18, the team looked at the health of 5,532 U.S. adults to find out how common these liver diseases are, under the new characterization.

They discovered that MASLD is quite widespread, affecting 4 out of 10 adults. Meanwhile, MetALD and ALD affect a smaller percentage – 1.7% and 0.6% of adults, respectively.

Hispanic adults showed a higher prevalence of MASLD (47% vs. 40%) than other racial and ethnic groups, a dramatic increase from a 2014 study of more than 6,800 people that showed a prevalence of 29% among Hispanics.

The latest finding points to the importance of early screening and intervention, particularly in communities that may be at greater risk. However, the new study did not find significant differences in the rates of advanced liver damage among the different racial and ethnic groups.

The NHANES data provide a detailed look at the health and nutrition of the U.S. population. To identify cases of liver disease, the study researchers looked at specific markers like liver fat levels and liver stiffness, along with enzyme levels in the blood that indicate liver health. Alcohol consumption was also taken into account to differentiate between metabolic and alcohol-associated liver diseases.

MASLD is associated with metabolic diseases, reaching an estimated prevalence of 65% in overweight patients, 90% in morbidly obese patients and up to 70% in patients with type 2 diabetes.

Groups at greater risk for MASLD include men, adults older than 40, individuals with health insurance, those with higher body mass index and people with other health issues like diabetes, high blood pressure, high triglycerides and low levels of good cholesterol. Interestingly, the study found that Black individuals had the lowest risk of developing MASLD compared with other groups.

The higher prevalence of MASLD among Hispanic adults may be due in part to a genetic predisposition as well as higher rates of diabetes and obesity, the study authors suggested. This points to a need for targeted public health initiatives to address the specific risk factors that might be contributing to this increased risk in the Hispanic community.

Although MASLD was the most common type of liver disease found in this study, the researchers also uncovered substantial rates of MetALD and alcohol-associated liver disease. For MetALD, the study showed that men and individuals with a higher BMI were at a greater risk, and Asians were at lower risk. Surprisingly, the only factor that appeared to lower the risk of ALD was having health insurance, though the reasons for this are not clear.

The researchers cautioned that the true prevalence of MetALD and ALD may actually be higher than the study indicates. These conditions can be tricky to diagnose accurately, so some cases may go unrecognized.

The high prevalence of MASLD highlights a pressing public health concern. Early detection and management of MASLD and its risk factors, such as obesity and diabetes, are key to preventing more severe liver problems down the road.

The study authors called for more research to explore why these disparities exist and how to reduce the burden of liver disease, particularly in groups that are most at risk. They also stressed the need for greater awareness about liver disease among all health care providers and the public to promote early detection and lifestyle changes that can help prevent disease progression.